Computer controlled telephone answering system

ABSTRACT

A computer controlled telephone answering system to serve a large number of subscribers over a vast geographic area, utilizing a plurality of remote site trunk concentrators adjacent to each telephone company central office to reduce the number of trunk lines required to service subscribers. A central site of this answering system, serving as a facility to answer calls relayed through the remote sites, also includes a trunk concentrator to further reduce the number of trunk lines to operator positions. A computer at the central site controls the entire system, determines switching paths from a subscriber line through the concentrator, to an operator, furnishes answering information to operators and stores instructions for answering incoming messages. The logic of the system permits any operator to answer any incoming telephone call on any subscriber line in the system promptly, economically and correctly.

This application is a continuation in part of prior application Ser. No.392,634 filed on Aug. 29, 1973, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to a computer controlled telephone answeringsystem and more particularly to a computer controlled telephoneanswering system covering a wide geographic area based on a plurality ofremote site and central site trunk concentors which minimize andoptimize the number of trunk lines required in the operation of atelephone answering service. The trunk concentrator includes analog,single wire switching system using analog switches in matrix form whichenable the telephone answering system, under computer control, todetermine a free path from the input side of each sequential analogswitching matrix to the output side and eventually to a computerterminal of the operator who will answer the call. The system includes:remote site concentrators and central site concentrators, which reducethe number of trunk lines necessary to connect subscriber telephones toa central site answering service office; a special purpose digital logicfor switching control, command verification, ring detection and datacommunications to and from the central answering service office; acentral computer for control of the system and storage of subscriberdata and messages; and an operator console including a computer terminaland display for operator answering of individual calls processed by thesystem.

2. Description of the Prior Art:

Telephone answering systems are well known in the prior art and need notbe described specifically here.

The prior art also discloses a number of switching systems forminimizing the number of trunk lines required between a telephonecompany central office and the switchboard of a telephone answeringservice. U.S. Pat. No. 3,002,054, as an example, discloses a trunkconcentrator for telephone answering service for installation andoperation in a telephone company central office which enables areduction in the number of trunks required to connect each subscriberline to a remote telephone answering service. It is uncertain, however,what level of reduction occurs within such a system and whether theconcentrator can be economically utilized in large scale answeringsystems covering a wide geographic region and numerous telephone companycentral offices. It also appears that this system requires aconventional switchboard and conventional operator positions, alimitation not necessitated in the system of the present invention.

The system of the present invention is based upon a number ofstatistical factors observed in the study of a telephone answeringsystem. A telephone answering service has a relatively large number ofsubscribers whose telephone lines are connected to the answering servicelines at a telephone company central office. For every 512 subscriberlines so connected, only a small percentage will be in use at any onetime. For every 512 subscriber lines served by a telephone answeringservice, statistics indicate that only eight of said lines are active atpeak times, and as few as none to two are active in non-peak times.However, in a conventional system, there must be positions on ananswering service switchboard for all 512 lines. An answering serviceoperator normally has a switchboard servicing 100 subscriber lines. Withsome effort, an operator can reach to the boards at either side of herposition to cover another 100 or 200 lines, if she is not busy. Presenttelephone answering systems, however, provide no way to direct anincoming call on a given subscriber line to any operator position whichis not busy. These calls must be directed to the operator position onthe specific switchboard to which the subscriber's line is connected,regardless of the current workload of the operator. This results in aconsiderable lack of flexibility and unnecessary operating costs for atelephone answering service.

The system of the present invention is designed to minimize the numberof trunks required to service the subscriber of a telephone answeringservice through the use of at least two trunk concentrators which areunder the operational control of a computer. A first type of trunkconcentrator, of which there may be more than one, is located at aremote site, perferably adjacent to a telephone company central officeserving individual subscribers. For each 512 subscriber lines cominginto each remote site from a single telephone company central office,there is a analog switching matrix which will switch any one of the 512incoming lines to any one of eight outgoing trunks which transmitsignals to the answering service central site. Each remote site also hasa special purpose digital control unit to control and verify theoperation of the analog switching matrices, a digital memory to holdtemporarily command messages for forwarding to the central site of theanswering service, and a digital logic for ring detection, switchcontrol and message verification.

Each remote site of the answering service is connected to a central siteat which the calls are actually answered by operators. For every 128trunks reaching the central site, there are up to sixty-four operatorpositions, each of which is able to answer any one of the 128 trunkscoming into the central site. To accomplish this, a central siteconcentrator is utilized which is a 128 by 64 analog switching matrixunder the control of a central site computer. Each operator position isbasically a computer input-output terminal with a keyboard, a cathoderay tube (CRT) display, and a memory and control unit. The central sitecomputer, in addition to a control program for the entire system, alsocontains within its memory the pertinent information required by anoperator to answer each incoming call. As the computer recognizes a callto be answered, it determines by the table look-up, which operatorposition if free to answer the call and sends the pertinent answeringinformation to the operator terminal to which it will direct the call.After the operator receives the call and takes the caller's message, theoperator will key the incoming message into the computer where it willbe stored until subscriber calls for his messages. In this fashion, thesystem of the present invention minimizes the chance of operator errorin answering calls, in taking messages, and in giving messages to thesubscriber. It also maximizes the use of operator labor by providing acomputer based retrival system rather than a manual retrival system.

The present embodiment of the system, as described herein, accomodatesup to 1,024 subscriber lines at each remote site, which lines areconcentrated to 16 trunk lines going to the central site. Each centralsite can handle, in a typical embodiment, 128 trunk lines from variousremote sites; thus eight remote sites serving a total of 8,192subscriber lines, as illustrated in the drawings; any one of whichsubscriber lines can be answered at any operator terminal. Theflexibility of this system is impossible to achieve in any othertelephone answering system.

SUMMARY OF THE INVENTION

This invention pertains to a computer controlled telephone answeringsystem which, through the use of a plurality of trunk concentrators, isable to service a large number of subscribers over a wide geographicarea, while minimizing the number of trunk lines and operators toservice these subscribers. The system includes remote sites preferablylocated adjacent to telephone company central offices, and a centralsite having a computer based control system with terminals for operatorswho answer calls.

Each remote site serves as an entry point for the subscriber lines froma nearby telephone company central office. At the remote sites thesesubscriber lines enter through a standard telephone company deviceaccess arrangement. The output from this equipment then is wired to ananalog switching matrix or a remote trunk concentrator. Each remote siteconcentrator is capable of concentrating 512 incoming subscriber linesdown to a maximum eight outgoing trunk lines to a central answeringservice site. The remote site also contains the digital control, memoryand transmission equipment necessary to operate its trunk concentrator,to determine which lines should be answered and to service theconnection of subscriber lines to outgoing trunks to the central site.When a subscriber line is to be answered under computer control, a paththrough its analog switching matrix is determined, the signal istransmitted by an active line which exists from the the central site.

The central site serves as the actual answering location in the system.It receives incoming calls from the remote sites and, by means of asecond trunk concentrator, switches an incoming call on any one of the128 trunk lines, to any available operator position of the 64 providedin the central site under computer control. The computer at the centralsite also stores the relevant information required by operators toanswer each call. Each operator at the central site is equipped with acomputer terminal having a keyboard entry system and a cathode ray tubevisual display. When the computer determines a free path from a ringingline through the remote site concentrator and the central siteconcentrator an operator position, it directs the control logic of eachconcentrator to make the necessary connections and forwards to theoperator's display all the information which is operator requires toanswer the call. While answering the call the operator keys in theincoming message and verifies it on her display. After completion of thecall, the operator forwards the incoming message from her terminal tothe central computer and is free to receive another call. Theflexibility of the system of the present invention is such that, in atypical installation, any one of 8,192 subscribes lines can be answeredby any one of 64 operators with each call being answered correctly andunhurriedly.

The flexibility of the present system is due to large part to the trunkconcentrators. The remote site concentrators utilize 512 bidirectionaleight-to-one analog switches, each of which will allow any one of eightsignals to pass through it in either direction. A three level digitalcode is used to select the signal. Sixty-four analog switches areconnected to select any one signal from 512 possible signals. Eight such512-to-one matrices are put together to form a 512-to-8 matrix for theremote site concentrators. More than one such matrix may be used at anyone site. An available free path through the matrix is determined undercomputer control. The trunk concentrator permits the number of trunksgoing to the central site to be reduced from 512 to eight or less fromeach remote site. An incoming call on any one of the 512 lines into aremote site concentrator can be forwarded to the central site throughany one of the non-active trunks, which need not be more than eight.

Another trunk concentrator is located at the central site. In a typicalconfiguration, each central site concentrator has 128 trunks coming infrom remote sites. In some cases a small portion of these 128 trunk willbe used for outgoing calls. The central site concentrator directs eachincoming call on any one of the 128 trunks to any one of 64 operatorpositions which may be free to answer the call. Thus the central siteconcentrator has an analog switching matrix of 128 by 64. Basically itutilizes the same eight-to-one bidirectional analog switch, arrayeddifferently. Sixteen eight-to-one switches form a 128-to-1 switch.Sixty-four of these 128-to-1 sections are put together to form a128-to-64 analog switch.

The flexibility and economic feasibility of the system of the presentinvention is further enhanced by the use of single wire switching in theanalog matrices of the concentrators. Each incoming subscriber line hastwo wires. In the concentrators, one of these wires is connected to acommon ground. The other wire is connected to one of the eight-to-onebidirectional analog switches, and serves to carry the audio signals.The use of this signal wire switching reduces the number of switchesrequired in the system by one-half.

In sum, the computer controlled telephone answering system of thepresent invention permits in the preferred embodiment any one of 8,192subscriber lines coming from a plurality of telephone company offices tobe answered correctly and promptly by any one of up to 64 operators at acentral answering service location.

The telephone answering system of the present invention has otherapplications besides the traditional telephone answering service. Forexample, it may be used as a private branch exchange serving a largeoffice or company, through its concentrators, and the answering serviceneed not be physically located in the office it serves. It may also beused as a telephone order system for mass merchandising companyreceiving incoming orders from a vast georgraphic area at one centrallocation.

It is, therefore, the principal object of this invention to provide animproved telephone system for use by telephone answering services orothers who receive a large volume of incoming calls.

It is a further object of this invention to provide an improved trunkconcentrator analog switching system for use with a telephone answeringsystem.

It is a further object of this invention to provide a new and improvedtrunk concentrator analog switching system for minimizing the number oftrunk lines required to answer a finite number of subscriber telephones,thereby reducing the trunk costs of a telephone answering service.

It is a further object of this invention to provide a telephoneanswering system which enables any incoming call to appear at anyoperator position and be answered correctly and promptly.

It is still a further object of this invention to provide a computercontrolled telephone answering system in which connections between anincoming call and the answering operator are achieved by means of acomputer controlled analog switching system.

It is yet another object of this invention to provide a telephoneanswering system in which the information required to answer an incomingcall to a subscriber is stored in a computer and delivered to theoperator who is assigned to answer the call, and in which the incomingmessage taken by the operator is inputted and stored in the computeruntil called for by the subscriber.

Further objects, features and advantages of the present invention willbecome readily apparent from reading the accompanying detailedspecification which will be written with reference to examples ofembodiments shown in the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration in block diagram form of a preferredembodiment of the computer controlled telephone answering system of thepresent invention illustrating the interrelationship of its majorsubsystems.

FIG. 2 is a block diagram illustrating the physical equipment at aremote site of the computer controlled telephone answering system ofFIG. 1 and the interrelationship of the major component units of thisequipment.

FIG. 3 is a block diagram illustrating the system trunk connectionsbetween a remote site and the central site of the system of FIG. 1.

FIG. 4 is a functional block diagram illustrating the communicationlinks between the operator positions and the other subsystems of thesystem of FIG. 1.

FIG. 5 is a functional block diagram illustrating the system controlunits at the remote and the central sites in the system of FIG. 1.

FIGS. 6 and 7 are block diagrams of the central site computer system ofFIG. 1 and the interfaces to the operator terminal units.

FIG. 8 is a functional block diagram of the central site concentrator ofthe system of FIG. 1.

FIG. 9 is a schematic illustration of the analog switch as utilized inthe remote site concentrator of the system of FIG. 1.

FIG. 10 is a schematic drawing of the control circuit on a line controlcard serving 32 subscriber lines entering the remote concentrator ofFIG. 1.

FIG. 11 is a schematic drawing of the ring multiplexer on the controlcard of FIG. 10.

FIG. 12 is a schematic illustration of a line control card illustratingthe input of one subscriber line to the 8-to-1 bidirectional analogswitch as it appears on a line card in the remote concentrator,illustrated in FIG. 10.

FIG. 13 is a block diagram of the remote site control unit and memory.

FIG. 14 is a block diagram of the central site control unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, and in particular to FIG. 1, wherein likereference numerals refer to like components, the computer controlledtelephone answering system of the present invention, designatedgenerally by reference numeral 20, is illustrated diagrammatically in apreferred embodiment. The invention described herein is moreparticularly concerned with the analog switching and control systemsrequired to handle incoming calls delivered to a telephone answeringservice over telephone company lines through standard telephone companyequipment.

All telephones are connected through switching circuits in one or moretelephone company central offices. Subscribers to a telephone answeringservice and connected to the answering service by the extension of apair of wires from the subscriber's position on the telephone officeframe to a device access arrangement provided by the telephone companyat the location of the answering service. In the present state of theart, a telephone answering service usually serves only one or morecollocated or geographically proximate telephone company central officesto be economically feasible and avoid the high cost of trunk lines. Thetelephone answering system 20 of the present invention overcomes thiseconomic limitation through the means described hereinafter.

As illustrated in FIG. 1, the system 20 serves telephone answeringservice subscribers 22 whose telephone lines 24 are connected normallyto a telephone company central office 26. When a subscriber 22 desiresto be connected to a conventional telephone answering service, a secondpair of wires is connected from the telephone company central office tothe office of the answering service. Depending on applicable tariffs,which vary from community to community, the subscriber may be liable fora mileage charge for a trunk line to the answering service. System 20,to minimize such possible trunk line costs, includes one or more remotesite units 28, each of which is located in near proximity to a telephonecompany central office 26. Each subscriber 22 is connected to a remotesite unit 28 through a trunk line 30, running from the central office 26to the remote site unit 28. In the preferred embodiment, illustrated inthe drawings, 1,024 subscribers 22 are connected to each remote siteunit 28 by separate trunk lines 30. Within each remote site unit thereis a control unit and an analog switching matrix or trunk concentratorin which these 1,024 trunk lines 30 are concentrated by the remote siteconcentrator 32, as hereinafter described, down to 16 or less trunklines 34 which lead to a telephone answering service central site 36.

In the preferred embodiment illustrated in the drawings, the centralsite 36 serves remote site units 28: Hence, 128 trunk lines 34 enter thecentral site, where they are then concentrated by a central siteconcentrator and control unit 38, as hereinafter described, to 64 trunklines 40 linked to operator position 42 under the control of a centralsite computer 44. Central site computer, in the preferred embodiment, ismodel SPC-16/65, manufactured by General Automation, Anaheim, Calif.Central site computer 44 serves to control system 20 by determininganalog switching paths through the analog switching matrices of theremote site concentrators 32 and through the central site concentrator38 to operator position 42, while supplying from its memory answeringinformation to operator positions 42 and storing messages accepted atoperator positions 42 for later delivery to subscribers 22. Theindividual units, subsystem and operation of computer controlledtelephone answering system 20 will be disclosed in detail in thesucceeding sections of this specifications.

Referring now to FIG. 2, wherein there is illustrated a block diagram ofphysical equipment located in a remote site unit 28 of telephoneanswering system 20, the subscriber lines 30 enter the remote site unit28 through a standard telephone company device access arrangementequipment 46, such as a CD-6 (Bell System) voice connection orequivalent. All wires 48 through 58 are connected to terminals locatedwithin the remote sites unit 28 as described hereinafter. The remotesite unit 28 includes, in the embodiment illustrated in the drawings, aremote site concentrator and control unit 32 consisting of two analogswitching matrices 60, 62, each of which can accept up to 512 subscriberlines 30 and concentrate the same to a maximum of eight outgoing trunklines 34, in such a way that any one of the 512 subscriber lines 30 maybe switched into any one of the eight outgoing trunks 34 to the centralsite 36. The remote site unit 28 includes a remote site digital controland memory unit 64, which stores and retrieves digital messagespertaining to switch control, command verfication and ring detection,connected to the analog matrices by a buss switch 66. The remote sitedigital control and memory unit 64 is further illustrated in FIG. 13.The remote site unit 28 also includes communication logic 68 to controldigital data transfer to and from the central site computer 44 through acommercially available VADAC 3400 data set 70 over a dedicated trunkline 72. All the digital control, memory and communication units in theremote site 28 are duplicated by secondary systems 64a through 72a inthe event of failure of the primary system. The back-up trunk line 72ais an automatic dial line which is switched in automatically upondetection of a failure in the primary system. The sixteen outgoing trunklines 34 from analog switching matrices 60, 62 go directly to thecentral site concentrator and control unit 38. The equipment in a remotesite unit 28 can fit into two standard cabinets of about 45 cubic feeteach and requires no personnel for its operation. Hence the remote siteunit 28 can be conveniently located physically adjacent to a telephonecompany central office 26, and through its 512-to-8 reduction in trunklines, it can significantly reduce the cost of connecting subscriberlines 24 to an answering service central site 36. All equipment shown inFIG. 2 under the general reference numeral 32 was specifically designedand built for system 20, with the exception of the Vadac sets 70.

FIG. 3 illustrates in block diagram form the telephone line connectionswithin both the remote suit unit 28 and the central site 36.

FIG. 4 illustrates the communication interfaces of system 20 in afunctional block diagram. System 20 is basically under the control of acentral site computer 44 located at the central site 36. Digital controlmessages are sent to the remote site concentrator and control unit 32through communications logic 68 over dedicated trunk lines 72. Remotesite concentrators 60, 62 each have up to sixteen trunks 34 deliveringtelephone calls to the central site concentrator and control unit 38,which contains a 128-to-64 analog switching matrix which functionselectronically in a similar fashion to the analog switching matrices 60,62. After the control unit 64 (illustrated functionally in FIGS. 2, 3,and 13) of the remote site unit 32 has determined that a subscriber line30 is ringing and has rung the number of times stored in the remote sitecontrol and memory, the remote site unit 64 sends a digital message tothe central site computer 44 to that effect. The computer 44, by a tablelook-up, determines a free path through one of the remote site analogswitching matrices 60, 62 of a remote site concentrator 32, to a trunkline 34 to a central site concentrator 38 and through central siteconcentrator 38 to a trunk line 40 from central site concentrator 38 toan available operator position 42. After the central site computer 44determines such paths, it issues digital data messages to the remotesite control unit 64, via control line 72, and the central siteconcentrator 38, via control line 76, to set switches to enable theringing subscriber line 30 to be switched to an available operatorposition 42. These control messages from the central computer 44 to theremote control unit 64 and to the central site concentrator control unit104 are sent over the digital data lines 72 and 76 respectively (FIG.5). At the same time the central site computer 44 notifies the operatorposition 42, via control line 74, which is to receive the incoming callthat the call will be switched to that particular position, andfurthermore the central site computer 44 will send to the operatorposition 42, for its memory, identifying information such as thesubscriber's name, telephone number, i.e., what line is to be answered,and answering instructions. This information is forwarded digitally tothe operator position 42 over a control line to a controller 114(illustrated in FIG. 7) and then to the operator position 42 for displayon cathode ray tube visual display 112 (FIG. 1). When the operator isready to answer the call, the operator signals the central site computer44 by a function key on her keyboard 110. Upon receipt of this digitalmessage, the computer sends a switching command to the remoteconcentrator and control unit 32 through the remote site control unit64. The connection through to the operator is made and the operatoranswers the call. As the operator receives from the caller incominginformation to be retained and later forwarded to the subscriber, shekeys this information into the controller 114 following a format on thecathode ray display tube 112. The keyed-in information also appears onthe cathode ray tube display 112 for visual review and correction by theoperator. After the call is completed and the operator has verified themessage, she signals the central site computer 44 and controller 114 toreceive and send the message, respectively. The computer 44, on a timeavailable basis, asks the controller 114 for the message. The operator,meanwhile, is available to receive another call.

FIG. 5 illustrates in block diagram form the functional logic in theremote site unit 28 and central site 36. The remote site unit 28, inthis embodiment, includes subscriber lines 30 entering the analogswitching matrices 60, 62 of the remote site concentrator 32 on linecontrol cards 90 (illustrated in detail in FIGS. 11, 12 and 13). Theline address decoder 92 is also on these cards. Trunk lines 34 to thecentral site concentrator 38 exit from line control cards 90. The remotesite control logic 64, 68 includes a timing set 94, a line interface 96,a buffer memory 98 and a concentrator address decoder 100. A data set 70serves as a communication link between the remote site unit 28 and thecentral site 36. FIG. 13 illustrates in block diagram the interrelationsamong the functions of remote site control unit 64.

The central site unit 38 is contained in three functional units. Thecentral site concentrator and control unit 38, including control logic102 and analog switching matrix 104, functions in a manner similar tothe remote site unit 28 insofar as its control logic 102 and its analogswitching matrix 104 is concerned. The central site computer 44 has itsown logic. The central site communications center 106 controls all thedata transfers within the system. Communications center 106 is basicallya model DMA multiplexer available from General Automation for use withits model SPC-16/65 computer. All equipment shown in FIG. 5 under thegeneral reference numeral 38 was specifically designed and built forsystem 20.

FIG. 6 illustrates the configuration of the central site computer 44,which as stated previously is a model SPC-16/65 made by GeneralAutomation, Anaheim, Calif, and its major component parts andrelationships thereto as further described in configuration with FIGS. 7and 8. The principal feature of computer 44 is the vast memory capacityfor storing the subscriber information required to be sent to theoperator positions 42 so that any operator can answer any call.Additionally, the computer 44 must store all incoming messages forsubscribers taken by the operators until they are called for by thesubscribers.

FIG. 7 illustrates in block diagram form the relationship of theoperator positions 42 to the central computer 44. Operator positions 42are interfaced through multiplexer 108, four to a channel. Each operatorposition 42 contains a keyboard 110, a cathode ray tube visual display112 and a telephone head set. Each group of four operator positions isserved by one or more controller units 114 which refresh the cathode raytube visual display screens 112 and serve as buffer memory. Eachcontroller 114 is connected directly to the multiplexer 108. Multiplexer108 is the DMA model commercially available from General Automation anddesigned to operate with the SPC-16/65. Computer 44 also available fromGeneral Automation. The disk memory units 101 illustrated in FIG. 6 arethe Caelus model 303 units. The card reader 103 is the model M200 ofDocumentation. The line printer 105 is the model 2100 of TalleyIndustries. The keyboards 110 and controllers 114 are the model MRD 780made by Applied Digital Data Systems.

FIG. 8 illustrates in detail the functional configuration of the centralsite concentrator and control unit 38. Central site concentrator andcontrol unit 38 includes an analog switching matrix 104 which, in theembodiment illustrated in the drawings, is a 128-by-64 matrix. Matrix104 further concentrates the 128 trunk lines 34 from the remote siteconcentrator 32 to a maximum of 64 lines 40 to the operator position 42.The number of operator positions 42 and the lines 40 to operatorpositions can vary according to the volume of calls received into system20. Some lines 41 exiting from switching matrix 104 can be used fortrace calls, the number varying according to the volume of such calls.The control logic 102 for central site concentrator and control unit 38is similar to that for the remote site unit 28 except for the ringdetection logic which is not in the central site control logic 102, asillustrated in FIG. 14. Central site control logic 102 has a buss switch103 and is connected to computer 44 over data line 76. It also has aback-up logic 102a, 106a and a back-up dial line 76a. Since the centralsite 36 is manned by human operators, some configurations may reserve upto sixteen of the trunk lines 34, at least one per remote concentrator32, for outgoing calls originated by the operators, said trunkshereinafter referred to by the reference numeral 116. Lines 116 wouldhave automatic dial feature and would exit from the central siteconcentrator 38 through standard telephone company CD-7 equipment orequivalent.

FIG. 9 illustrates the use of an eight-to-one bidirectional switch 120in the analog switching matrices 60 and 62 of the remote siteconcentrator 32 and of the central site concentrator 38. Analog switch120 is a commercially available AM3705 eight-channel MOS analog switch.Each analog matrix 60, 62 is a 500 twelve-to-eight bidirectional analogswitch built from 512 individual analog switches 120. Each eight-to-oneanalog switch 120 will allow any one of eight signals to pass through itin either direction. The signal is selected by a three bit digital code.Each switch 120 also has an enable pin which permits the utilization ofa large number of such switches 120 to form the analog matrices 60, 62of the remote concentrator 32 and the analog matrix 104 of the centralsite concentrator 38. FIG. 9 illustrates in a fragmentary view how 64 ofsaid analog switches 120 are connected to select any one signal from 512lines. Also illustrated in FIG. 9 is the use of eight of these 500twelve-to-one sections to form each 500 twelve-to-eight analog switchingmatrix 60, 62 in the remote site concentrator 32.

The analog matrix 104 of central site concentrator 38 can switch any oneof 128 lines 34 into any one of 64 lines 40 to the operator position 42(FIG. 8). It uses the same analog switching technique and analogswitches 120 as the remote site concentrator 32 but is arrayed to formits 128-to-64 matrix. Each section will have 128 eight-to-one analogswitches 120 forming a 128-to-8 switch. Eight such sections arerequired, thus utilizing 1,024 switches 120 in the complete matrix 104.

FIGS. 10, 11 and 12 illustrate one of the remote line cards 90 used inthe remote site concentrators. Each remote line card 90 has two primaryfunctions. These are:

a. to provide ring detection capabilities for monitoring the presence ofincoming calls on each subscriber line 30; and

b. to provide the matrix address decoding necessary for accessing any ofthe 512 AM3705 analog multiplexers 120 illustrated in FIG. 9.

The later function of the remote line card 90 therefore allows thecentral site computer 44 to switch any one of the 512 incomingsubscriber lines 30 to any one of the eight outgoing trunks via theremote line control card 90.

As illustrated in FIGS. 10, 11 and 12, the concentrator 32, 38 operateon the principle of a single wire switching. All the ring wires 50 areconnected to a common ground which, in the remote site concentrator 32,serve in the ring detection logic 122. The tip wires 48 serve as inputsto the analog multiplexer switch 120. The high impedance of switch 120enables an analog audio signal to pass in both directions over thesingle tip wire 48.

Each remote line card contains sufficient electronics for accessing anyone of 32 AM3705 analog switches 120 illustrated in FIG. 9. Each 512×8matrix 60, 62 of the type shown in FIG. 2, therefore, contains sixteensuch remote line cards 90. FIG. 10 shows one such remote line card 90minus the thirty-two analog switches 120 and their associatedelectronics. FIG. 11 is a more detailed representation of the ringdetect logic 122 shown also in FIG. 10. FIG. 12 shows one of thethirty-two analog switches 120 and its associated electronics which arepresent on each remote site line card 90.

The function of the ring detect logic circuit 122 may be described asfollows

FIG. 2 shows that the telephone company's standard access device 46(CD-6 or similar) delivers ring information to the remote siteconcentrator and control unit 32 of the telephone answering system 20,at which point said ring signal enters line control card 90 as describedsupra. This information is in the form of a switch closure betweenground and one of the RG leads shown in FIG. 11. That is to say, when acall to a subscriber is received at the telephone company, a switchclosure is implemented which shunts the appropriate RG lead to ground.There are, of course, 512 such leads; 32 to each of 16 remote line cards90. As shown in FIG. 11, the RG leads are inputs to an eight-to-onemultiplexer 124. Any of the eight input lines may be connected to theoutput by applying the proper binary code, D0 D1 D2, and by enabling theanalog switch at pin 10. In this particular application the remotecontrol card (FIGS. 5 and 13) imposes a 10 bit binary code D0-D9 on theremote site line card 90. Bits D0-D2 are used in the ring detect toaddress one of eight input lines. Bits D3, D4 are sent through atwo-line-to-four line SN74155 decoder 126 (FIG. 10) to enable one of thefour eight-line ring detection circuits 122. Bits D5-D9 are used toenable one of the 16 remote line control cards by means of an enablesignal (SEL) sent to the SN74155 decoder 126 and to the output gate ofthe ring detection circuit 122. Hence by sequencing bits D0-D9, eachring line from the 512 subscribers is checked for 0 volts. A ringingline will thereby be gated to the remote site control card so that thenumber of rings may be counted or so the termination of ringing may bereported. Any line not ringing will, of course, go unnoticed becauseeach input is tried to 5 volts through a 330 ohm resistor.

In addition to controlling the address of lines to the ring detectionlogic 122, bits D0-D9 are also imposed on four eight-bit Fairchild 9334addressable latches 128 as shown in FIG. 10. Each of the 32 digitaloutputs from these latches is used to enable one of the 32 AM3705 eightchannel analog switches 120 via their associated circuitry. A discussionof the addressing circuits is given below.

FIG. 12 shows one of the 32 eight channel analog switching circuits 130present on each remote line card 90. All inputs to this portion of theremote site line card are sent from the central site computer 44,through the remote site control card, and are imposed on the buffergates 127 shown in FIG. 10.

The logic of the sixteen control cards in the remote site concentratorand control unit 32 (32 of such cards if two analog matrices 60, 62 arepresent) is not illustrated in detail because it is conventional solidstate logic. This control logic on the control card stores the number ofrings required before a subscriber line 30 is answered; counts thenumber of rings on a ringing line and compares this number with thethreshhold stored. It also can receive and acknowledge eight basicdigital messages:

Connect line x to trunk y;

take line x off-hook;

place line x on-hook and disconnect from trunk y;

deactivate all lines and trunks;

load ring count;

send ring count;

ring out compares;

ring count exceeds present by two.

The central site concentrator and control unit 38 operates similarly tothe remote site concentrator and control unit 32 except for certainbasic differences. Primary among these is the absence of any ringdetection logic, ring count logic, off-hook and related digitalmessages. Hence the central concentrator and control unit 38 needs toreceive and acknowledge only three basic digital messages:

connect;

disconnect;

rest.

Thus the central site concentrator 102 is basically a large switchingmatrix, in the preferred embodiment, a 128-to-64 switch, utilizing thesame analog multiplexer 120 as a switch, as in the remote siteconcentrator 32.

System operation:

A typical step-by-step sequence of events for a normal call routedthrough the telephone answering system 20 may be described as follows

System 20 is a telephone answering system having a number of subscriber22 connected thereto. Each subscriber furnishes the system 20 with basicinformation such as the way he wishes his line answered, what type ofmessage to take, what questions to ask callers and after how many ringshe desires to have the telephone answered. All this subscriberinformation is stored in central site computer 44. Periodically centralcomputer 44 will send digital messages to each remote site control unit64 indicating predetermined number of rings for each subscriber line 30connected to its concentrator 32. Remote control unit 64 constantlyscans all subscriber lines 30 for a ringing condition. When a line 30 isdetected as ringing, a ground appears at the ring detection multiplexerin remote control unit 64. At this point, the ring is indicated to theremote site control unit buffer memory 98 which retrieves a word withanswer instructions from its memory, increments a bit to count therings, and compares the results to the predetermined number of ringsrequired for answering the line. If the prescribed number of rings hasnot been met, no message is sent to the central site computer 44 and thecontrol unit 64 goes on to scan the next line.

If the threshold of the predetermined number of rings has been met, thenthe remote site control unit 64 outputs a control message over itscontrol line 70 to the central site computer 44 stating that the ringingline has met the threshold for being answered. Upon receipt of thismessage the central computer 44 does a table look-up to determine whichtrunk lines 34 are available to the central site concentrator 38 andwhich operator position 42 is available. The computer 44 then determinesa path through both concentrators 60, 102 to an available operatorposition 42 and communicates its switching instruction to eachconcentrator 60, 102 via the digital code discussed supra, i.e.,addressing code on bits TR0-TR2.

At the same time a Connect bit is sent which clocks the trunk accessbits into the D flip flops 129 which have been properly enabled by theFairchild 9334 eight bit latches 128. When the trunk address codes havebeen loaded, a signal is sent to the central site computer 44 to thateffect. The computer 44 checks to see if the proper connection has beenmade, notifies one of the operator positions 42 off an in-coming call,and displays the necessary information on its CRT visual display 112,including the subscriber master record, answering instructions and acomplete format. The operator presses an off-hook button which is sentthrough the computer 44 to the appropriate remote site line card 90along with the trunk address code and the Connect signal. The Connectsignal again locks all data into the D flip flops 129 including theoff-hook data bit. The off-hook relay is pulled in and the operator canthen talk with the in-coming caller. The operator keys in any messages,completes the call an signals the computer 44 that the call has beencompleted by hitting a function key on the keyboard 110, sending adisconnect signal through the computer 44 to the remote site line cars90. This resets all the flip flops 129 and disconnects thecommunications path through the analog switching matrix 60. It is seen,then, that the ten data bits D0-D9 plus the trunk address codesdetermine exactly which analog switching path is chosen. Meanwhile, themessage is first stored in the controller 114 unti the computer 44 hastime and channels available to request it. After being sent to thecomputer 44, the message is stored in disk memory.

If the call should be from a subscriber, either calling for his messagesor to change his instructions, the operator first requests hisidentification number which she keys into the computer 44. Uponverification of identity, the computer 44 sends the stored message forthe subscriber to the operator cathode ray tube visual display 112 fordisplay and reading to the subscriber, one at a time. After each messagethe operator indicates to the computer 44 whether that message has beendelivered to the subscriber. The computer 44 then marks the deliveryrecord and creates a billing record.

If the subscriber desires to change his instructions, the computer 44will output to cathode ray tube visual display 112 the old instructionsand a format for new instructions. The operator then fills out theformat with the keyboard 110 and enters this data into computer 44,which updates its files.

As illustrated in FIGS. 2 and 8, all the control functions are backed upby alternate equipment. All the computer programs have error checkingroutines. If control messages are not received by a given unit or arenot acknowledged within a predetermined time limit, the message sequenceis reinitiated. If there is a failure on the second try, the back-upequipment is switched in automatically.

The following tables illustrate the source and destination of each ofthe digital messages utilized in system 20 and described in thepreceding paragraphs. In these tables the term "Processor" refers to thecentral processing unit (CPU) of computer 44; the term "CRT" refers tothe cathode ray tube visual display 112; "Central" refers to the centralsite concentrator and control unit 38; "Remote" refers to the remotesite concentrator and control unit 32.

    __________________________________________________________________________    EXPLANATION OF SYMBOLS                                                        __________________________________________________________________________     ##STR1##                                                                                         ##STR2##                                                   ##STR3##                                                                                         ##STR4##                                                   ##STR5##                                                                                         ##STR6##                                                  __________________________________________________________________________

                                      TABLE I                                     __________________________________________________________________________    INITIALIZATION                                                                __________________________________________________________________________     ##STR7##                                                                      ##STR8##                                                                                         ##STR9##                                                                      ##STR10##                                                  ##STR11##                                                                                        ##STR12##                                                 __________________________________________________________________________

                                      TABLE II                                    __________________________________________________________________________    NORMAL OPERATION                                                                                 ##STR13##                                                   ##STR14##                                                                     ##STR15##                                                                     ##STR16##                                                                                       ##STR17##                                                                     ##STR18##                                                                     ##STR19##                                                   ##STR20##                                                                                       ##STR21##                                                  THE OPERATOR (Z) IS NOW IN VOICE COMMUNICATION WITH                           SUBSCRIBER (X) AND IS TYPING IN THE MESSAGE ON THE                            CRT                                                                           NORMAL MESSAGE                                                                                   ##STR22##                                                   ##STR23##                                                                                       ##STR24##                                                   ##STR25##                                                                     ##STR26##                                                                     ##STR27##                                                                                       ##STR28##                                                                     ##STR29##                                                  __________________________________________________________________________

                  TABLE III                                                       ______________________________________                                         DIAGNOSTIC                                                                   ______________________________________                                        IF AN OFF HOOK COMMAND IS NOT SENT TO THE                                     PROCESSOR BEFORE THE RING COUNT IS THE                                        PRESET COUNT PLUS TWO RINGS THE FOLLOWING                                     MESSAGE WILL BE SENT BY THE REMOTE                                            CONCENTRATOR                                                                                ##STR30##                                                       IF THE PROCESSOR WISHES TO CHECK THE PRESET                                   SUBSCRIBER RING COUNT NO. THE FOLLOWING                                       COMMAND IS SENT                                                                ##STR31##                                                                                       ##STR32##                                                  ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                         NORMAL OPERATION ALTERNATIVES                                                ______________________________________                                        WHEN THE OPERATOR IS IN VOICE CONTACT WITH                                    THE SUBSCRIBER, RETRIEVAL FORMATS,                                            ORDER FORMATS OR SPECIAL FORMATS                                              CAN BE SOLICITED BY HITTING                                                   THE APPROPRIATE KEYS ON CRT (Z).                                              ______________________________________                                    

The following tables further illustrate a basic program and its relationto software structure providing the regulation of system 20.

Table I-A represents the overall design of the software structure.

Table II-A illustrates foreground processing of interrupts in system 20.

Table III-A illustrates executive level processing initiating theapplications level processing of system 20, terminating foregroundprocessing, and preparing system 20 for call acceptance.

Table IV-A illustrates the message flow through system 20 during normaloperation as controlled by the central processing unit.

Table V-A illustrates the sequence of events of the program of system 20when a call is received.

Table VI-A illustrates non-call application programs of system 20 whichis needed for proper system functioning.

                  I-A                                                             ______________________________________                                        SOFTWARE STRUCTURE                                                             ##STR33##                                                                

                                      II-A                                        __________________________________________________________________________    FOREGROUND PROCESSING                                                         DEVICE INTERRUPTS                                                             __________________________________________________________________________     ##STR34##                                                                     ##STR35##                                                                    __________________________________________________________________________

                                      III-A                                       __________________________________________________________________________    EXECUTIVE LEVEL PROCESSING                                                             EXECUTIVE DISPATCHER                                                  ##STR36##                                                                     ##STR37##                                                                                 EXECUTIVE SERVICES                                               *GET/RELEASE BUFFERS FROM BUFFER POOL                                         *GET/PUT BYTES FROM/TO BUFFERS                                                *QUEUE I/O TO DEVICE HANDLER                                                  *QUEUE WORK FROM TASK TO TASK                                                 *READ IN OVERLAYS                                                             __________________________________________________________________________

                                      IV-A                                        __________________________________________________________________________    MESSAGE FLOW                                                                   ##STR38##                                                                     ##STR39##                                                                    __________________________________________________________________________

                                      V-A                                         __________________________________________________________________________    CALL PROCESSING                                                               APPLICATION PROGRAMS                                                           ##STR40##                                                                                     ##STR41##                                                                                   ##STR42##                                                                                    ##STR43##                       *LOOKS AT QUEUE OF                                                                            *DISPLAYS CUSTOMER                                                                          *DISPLAYS ALL  *SCHEDULED WHEN CONTROL          CALLS WHICH ARE INFOMATION ON CURRENT        KEY IS DEPRESSED ON A            READY FOR AN    CRT           INSTRUCTIONS   CRT                              OPERATOR (RING                HAVING TO DO                                    COUNT VALUE HAS *ISSUES REMOTE/                                                                             WITH THIS      *TRANSFERS CONTROL TO            BEEN REACHED)   LOCAL VOICE   ACCOUNT ON     REQUIRED APPLICATIONS                            CONNECT       THE CRT        PROGRAM:                         *ASSIGNS                                                                      RESOURCES TO    *ISSUES CRT                                                   RETRIEVAL                                                                     CALL*           LOCAL VOICE                                                                   CONNECT                                                       ENTER MESSAGE                                                                 *ASSIGNS TRUNK                                                                ON REMOTE       *ISSUES OFF                                                                   HOOK                                                          *GETS A "CALL                                                                 CONTROL PACKET" *PUTS CRT IN                                                  WHICH CONTAINS  MODE WHICH                                                    ALL CONTROL     WAITS FOR                                                     INFORMATION     CRT KEYBOARD                                                  ABOUT CALL      TO DETERMINE                                                                  NEXT                                                          *ASSIGNS AN     FUNCTION                                                      AVAILABLE CRT                                                                                 *CALLS                                                        *IF ANY         INSTRUCTION                                                   RESOURCE IS     RETRIEVAL IF MORE                                             UNAVAILABLE     THAN ONE                                                      CALL IS LEFT ON INSTRUCTION FOR                                               QUEUE TO BE     THE SUBSCRIBER                                                ASSIGNED                                                                      RESOURCES WHEN                                                                AVAILABLE                                                                     *SCHEDULES MASTER                                                             RCD DISPLAY                                                                    ##STR44##                                                                                     ##STR45##                                                                                   ##STR46##                                       *SAVES MESSAGES ON                                                                           *ISSUES REMOTE/                                                                             *DISPLAYS ALL DELIVERED                         DISK FOR LATER  LOCAL DISCONNECT                                                                            AND/OR UNDELIVERED                              RECALL BY RETRIEVAL           MESSAGES FOR SUBSCRIBERS                                        *ISSUES CRT/LOCAL                                             *SCHEDULES DISCONNECT                                                                         DISCONNECT                                                                    *PUTS CRT ON                                                                  AVAILABILITY QUEUE                                                            *PUTS CRT ON                                                                  AVAILABILITY QUEUE                                                            *PUTS REMOTE TRUNK                                                            INTO TRUNKS                                                                   AVAILABLE QUEUE                                               __________________________________________________________________________

                                      VI-A                                        __________________________________________________________________________    NON-CALL APPLICATION PROGRAMS                                                  ##STR47##                                                                                       ##STR48##                                                                                   ##STR49##                                                                                  ##STR50##                       *RESTARTS         SENDS RESET   *SNAPS SYSTEM                                                                              *PRINTS SYSTEM STATUS            SYSTEM IN         TO ALL REMOTES                                                                              STATUS TO    REPORTS                          CASE OF                         DISK                                          SYSTEM            *SENDS RESET TO                                             FAILURE           LOCAL                                                                         *PUTS CANNED                                                                  MESSAGE                                                                       ACCEPTANCE                                                                    FORMAT TO                                                                     ALL CRTS                                                     ##STR51##                                                                                       ##STR52##                                                                                   ##STR53##                                                                                  ##STR54##                       *SENDS            *ADDS NEW     *PUTS        *PUTS REMOTES/CRT OR             DIAGNOSTIC        ACCOUNTS INTO SUBSCRIBER   TRUNKS IN OR OUT OF              COMMANDS TO       SYSTEM        PHONE ON/OFF SERVICE                          EVERY REMOTE                    LINE DEPENDING                                                                ON HOURS OF  *ASSIGNS AN OPERATOR             DETERMINES                      SERVICE      TO A CRT                         STATUS OF                                                                     REMOTE                                       *SENDS RING COUNTS TO                                                         REMOTES JUST PUT INTO                                                         SERVICE                          *ISSUES RESET                                SERVICE                          IF FAILURE                                                                    OCCURS                                       *RESETS RING COUNT ON                                                         ANY INDIVIDUAL                                                                SUBSCRIBER                        ##STR55##                                                                    *PUTS OLDEST                                                                  MESSAGE                                                                       TO THE HISTORIC FILE                                                          FREEING THE MESSAGE                                                           DISK                                                                          __________________________________________________________________________

Thus it will be seen that the system of the present invention provides afeasible and economical solution to the technical anad cost problemsinvolved in a large scale telephone answering service. The use ofunmanned, remote trunk concentrators located adjacent to telephonecompany central offices provide a reduction of 64 to one in trunk linecosts to a large centralized answering service. The use of a centralconcentrator provides a further cost reduction of two-to-one in operatorlabor and equipment costs for operator positions. The elimination ofelectromechanical switchboards and the use of a computer controlledelectronic switching enabling any one of 8192 subscriber lines to beswitched to any operator provides a flexibility not otherwise available.The use of single wire analog switching reduces the number of switchesto one-half, providing a significant reduction in switching costs. Withthe multiplication of various units of equipment, the system of thepresent invention is capable of expansion to serve millions ofsubscribers over a wide geographic area at minimal costs.

It is to be understood that the above-described embodiments are butillustrative of the application of the principles of this invention.Numerous other arrangements and application may be devised by thoseskilled in the art without departing from the spirit and scope of theinvention.

.[.I.]. .Iadd.We .Iaddend.claim:
 1. A computer controlled telephoneanswering system serving the subscribers of at least one telephonecompany central office comprising:a remote site in close geographicproximity to said telephone .[.companay.]. .Iadd.company.Iaddend.central office; a central site at which the telephones ofsubscribers are actually answered, said central site serving at leastone remote site; .[.a.]. digital computer .[.and communicationscenter.]. .Iadd.means .Iaddend.located within said central site forsupervision and control of said telephone answering system includingregulation of said remote .[.sites and for storing and retainingsubscriber information within said system.]. .Iadd.site.Iaddend.; atleast one remote site .[.trunk.]. concentrator and .Iadd.an associated.Iaddend.control unit located at .[.each.]. .Iadd.said .Iaddend.remotesite; .Iadd. a plurality of answering service subscriber lines connectedto said telephone company central office; .Iaddend. a .Iadd.first.Iaddend.plurality of .[.answering service subscriber.]. .Iadd.trunk.Iaddend.lines connected from said telephone company central office tosaid remote site concentrator .[.and control unit.].; at least onecentral site concentrator and .Iadd.an associated .Iaddend.control unitlocated at said central site; a .Iadd.second .Iaddend.plurality of trunklines .Iadd.connected .Iaddend.from .[.each of.]. said remote siteconcentrator .[.and control units.]. to said central site concentrator.[.and control unit.]., the number of said .Iadd.second plurality of.Iaddend.trunk lines being substantially less than the number of said.[.answering service subscriber.]. .Iadd.first plurality of trunk.Iaddend.lines; said remote site concentrator and .Iadd.associated.Iaddend.control unit.Iadd., under control of said digital computermeans, .Iaddend.having switching capability to switch any of said.[.incoming.]. subscriber lines through said remote site concentrator toany of said .[.outgoing.]. trunk lines leading to said central siteconcentrator .[.and control unit.]., thus reducing the number of trunklines connected to said central site answering said subscribertelephones; a plurality of telephone answering operator positions withinsaid central site, the number of said telephone answering operatorpositions numbering less than the number of said .Iadd.second pluralityof .Iaddend.trunk lines entering said central site concentrator, each ofsaid telephone answering operator positions .[.connected.]. .Iadd.beingconnectible .Iaddend.to said central site concentrator; said centralsite concentrator and .Iadd.associated .Iaddend.control unit.Iadd.,under control of said digital computer means, .Iaddend.having.Iadd.switching .Iaddend.capability to switch any of said .Iadd.secondplurality of .Iaddend.trunk lines through said central site concentratorto any of said telephone answering operator positions; digital datatransmission means connected to said remote site .[.concentrator and.].control unit.[.,.]. .Iadd.and .Iaddend.said central site .[.concentratorand.]. control unit and said digital computer .Iadd.means.Iaddend.;.[.a.]. .Iadd.data storage means associated with said .Iaddend.digitalcomputer .Iadd.means .Iaddend.located within said central site .[.forsupervising the control, line selection, and switching functionsrelating to said system, and.]. for storing and retaining subscriberinformation .Iadd.data .Iaddend.within said system.Iadd., theinformation data for each subscriber comprising a predetermined numberof rings at which the subscriber's line is to be answered.Iaddend.; saidremote site .[.concentrator and.]. control unit including ring detectionmeans for repeatedly and sequentially scanning each of said subscriberlines to ascertain which of said subscriber lines are in active ringingcondition; .[.said remote site concentrator and control unit havingdigital transmission means associated with and responsive to said remotesite concentrator and control unit ring detection means;.]. said digitaltransmission means .[.connected to said central site control unit for.].transmitting .[.an.]. .Iadd.a subscriber .Iaddend.identifying digitalsignal .Iadd.from said remote site control unit .Iaddend.to said.[.central site control.]. .Iadd.digital computer .Iaddend.means uponthe detection of a ringing subscriber line .Iadd.having itspredetermined number of rings.Iaddend.; .[.said digital computerconnected to said central site digital transmission means through saidcentral site control unit for receiving an identifying digital signalupon detection of a ringing subscriber line;.]. said .Iadd.digital.Iaddend.computer .[.interconnected to said remote site concentrator andcontrol unit and said control site concentrator and control unit throughsaid digital transmission means for establishing.]. .Iadd.meanscontrolling the establishment of .Iaddend.a subscriber line path throughsaid remote site concentrator and said central site concentrator to.Iadd.any of .Iaddend.said telephone answering operator positions.Iadd.upon receipt of an identifying digital signal.Iaddend.; saidremote .[.and central.]. site .[.digital.]. control .[.units.]..Iadd.unit .Iaddend.having .Iadd.a digital .Iaddend.memory .[.units.]..Iadd.unit for storing the predetermined number of rings for each ofsaid subscriber lines feeding said telephone company centraloffice.Iaddend.; .[.a buss switch connecting said remote and centralconcentrators to said control and memory unit;.]..Iadd. said digitalcomputer means controlling the transfer of said subscriber ringinformation data from said data storage means to the memory unit of saidremote control unit via said digital data transmission means. .Iaddend..[.a primary remote-site communications logic controlling digital datatransfers to and from said remote site; a remote site digital meanstransfering said data to and from said remote site; a dedicated controltrunk line connecting said remote and central sites carrying said data;said telephone answering operator positions being connected with saidcentral site concentrator and said data being directed through aproprity controller including a buffer memory and said positions alsobeing interfaced through a multiplexer; said central site concentratorand control unit having the capability to switch any of said trunk linesthrough said central site concentrator to any of said telephoneanswering operator positions..].
 2. The apparatus of claim 1 whereinsaid telephone answering operator positions comprise:.[.a.]. keyboard.Iadd.means .Iaddend.for entry of data signals in digital form by.[.the.]. .Iadd.an .Iaddend.operator; .Iadd.visual display.Iaddend.means for the visual display to the operator of data enteredfrom .[.said.]. .Iadd.an associated .Iaddend.keyboard .Iadd.means.Iaddend.or sent from said digital computer .Iadd.means.Iaddend.;.[.a.]. controller .Iadd.means .Iaddend.interfacing with said keyboard.Iadd.means.Iaddend., said visual display .Iadd.means .Iaddend.and saidcentral site digital computer .Iadd.means.Iaddend., said controller.Iadd.means .Iaddend.being responsive to digital command signals fromsaid keyboard .Iadd.means .Iaddend.and said digital computer.[., andsaid controller having a digital memory unit.]. .Iadd.means.Iaddend.;.[.telephone trunk lines from said central site concentrator to saidoperator position to enable said operator to answer subscriber telephonelines, and to originate telephone calls; and.]. all of said operatorposition equipment being controlled by said central site .Iadd.digital.Iaddend.computer .Iadd.means.Iaddend..
 3. The computer controlledtelephone answering system as defined in claim 1 wherein said remotesite concentrator and .Iadd.associated .Iaddend.control unit further.[.includes.]. .Iadd.include.Iaddend.:.[.remote line control cardshaving a ring detection logic providing means for ring detection andmeans to electrically count the number of rings upon each subscriberline;.]. a line address decoder to determine the appropriate connectionof a ringing subscriber line through said remote site concentrator; .[.adigital memory for storing a number representing the predeterminednumber of rings required to answer a subscriber line, thus.]..Iadd.means for .Iaddend.providing .[.a basis to report.]. ring, offhookand on hook status of each of said subscriber lines; a timing setproviding means to coordinate the activities of .[.aforesaid.]..Iadd.said .Iaddend.remote site concentrator particularly in scanningsaid subscriber lines and in relaying data through said remote siteconcentrator; .[.a concentrator address decoder acting in conjunctionwith said central site computer determining available trunk lines andpaths for transference of incoming and outgoing subscriber calls betweensaid remote site concentrator and said central site concentrator;.]..[.a.]. .Iadd.said .Iaddend.digital memory .Iadd.unit .Iaddend.includinga buffer, .[.comparing and matching subscriber data with data from saidring detect logic, said line address decoder, said timing set and saidconcentrator address decoder,.]. said buffer being a temporary storageof data necessary to activate said system with respect to a particularsubscriber line; an electrical counting means to count the number ofrings on each subscriber line; a comparison means to determine whetheran actual number of rings on any subscriber line meets a predeterminednumber of rings required for answering said subscriber line; a remotesite data set to receive and transmit digital messages between saidremote site and said central site; .Iadd.and .Iaddend. a line interfacecommunicating with said buffer .[.memory.]. and said timingset.[.;.]..Iadd.. .Iaddend. .[.a trunk line from said remote site dataset to said central site for high speed transmission and receipt of saiddigital data messages; and at least one trunk line from said remote siteconcentrator communicating said incoming and outgoing subscribercalls..].
 4. The computer controlled telephone answering system asdefined in claim .[.3.]. .Iadd.1 .Iaddend.wherein said remote site.[.concentrator and.]. control unit .Iadd.ring detection .Iaddend.meansto scan said subscriber lines comprises:.[.a.]. .Iadd.the .Iaddend.ringwire .Iadd.of each subscriber line .Iaddend.connected to ground;.Iadd.and .Iaddend. means for scanning on a periodic basis for a groundon .Iadd.the tip wire of .Iaddend.each subscriber line caused by acontrol closure .[.in said subscriber telephone circuit.]. resultingfrom a ring signal.
 5. The computer controlled telephone answeringsystem as defined in claim .[.3 wherein said means at said central siteresponsive to the receipt of said digital information concerning theringing condition of a subscriber line comprises.]. .Iadd.1 furthercomprising.Iaddend.:a data set .[.at said control site control unit.].capable of receiving and transmitting .Iadd.digital .Iaddend.messages;said digital computer .Iadd.means .Iaddend.at said central siteinterconnected to said remote site control unit .[.and said central sitecontrol unit.]. .Iadd.being .Iaddend.capable of interpreting .[.said.].digital messages and initiating digital commands in response thereto. 6.The computer controlled telephone answering system as defined in claim 1wherein said .[.digital computer.]. .Iadd.data storage means .Iaddend.atsaid central location further includes:digital memory units for storageand .[.retrival.]. .Iadd.retrieval .Iaddend.of all information pertinentto answering subscriber telephones and for storing and retrieving allmessages for said subscribers.
 7. The computer controlled telephoneanswering system as defined in claim 1 wherein said remote siteconcentrator control unit further includes:.[.a digital memory forstoring a number representing the predetermined number of rings requiredto answer a subscriber line; and.]. electrical counting means to countthe number of rings on each subscriber line; comparison means todetermine whether an actual number of rings on any subscriber line meetsa predetermined number of said rings required for answering saidsubscriber line; a set of digital messages in said digital memory.Iadd.unit .Iaddend.pertaining to each subscriber line; .[.at least onetrunk line from said remote location to said central location for.]..Iadd.said digital data transmission means providing .Iaddend.high speeddigital transmission of said digital messages .[.and receipt of responseto said digital message.].; and a data set to transmit digitally saiddigital messages to .[.and from.]. .Iadd.said .Iaddend.central sitelocation.
 8. The apparatus of claim 1 wherein said remote siteconcentrator comprises an analog matrix switching array.
 9. Theapparatus of claim 1 wherein said central site concentrator comprises ananalog matrix switching array.
 10. The apparatus of claim 1 wherein saidremote site and central site concentrators further comprise:.[.aplurality of telephone trunk lines entering said concentrators; apluality of telephone trunk lines exiting from said concentrators; thenumber of said exiting trunk lines being substantially less than thenumber of trunk lines entering thereto.]. a plurality of digital controlcircuits .[.for the control and operation of said trunk concentrator.].,with at least one digital control circuit for each .[.of said.].entering trunk .[.lines.]. .Iadd.line.Iaddend.; a switching matrixwhereby any one of said entering trunk lines may be interconnected toany .[.one of said.]. exiting trunk .[.lines.]. .Iadd.line.Iaddend.; abidirectional analog multiplexer in said digital control circuitsassociated with each individual entering line; the tip wire of eachentering trunk line being connected to the input of said analogmultiplexer, and the ring wire of each entering trunk line beinggrounded; the tip wire of each exiting trunk line being connected to theoutput side of said analog multiplexer; said analog multiplexer therebyserving as a single wire analog switch for interconnecting any enteringtrunk line to any outgoing trunk line; means responsive to a digitalcommand to connect a particular entering trunk line to a particularexiting trunk line such that said digital control circuit for thatentering trunk line is enabled, thereby connecting said entering trunkline to an available exiting trunk line; said concentrators therebybeing matrices of single wire bidirectional analog switches, andavailable electrical paths through said matrices being determined bysaid digital computer .Iadd.means.Iaddend.. .Iadd.
 11. A computercontrolled telephone answering system serving the subscribers of atleast one telephone company central office comprising: (a) a remote sitein close geographic proximity to said telephone company central office;(b) a central site at which the telephones of subscribers are actuallyanswered, said central site serving at least one remote site; (c) aplurality of incoming telephone lines of subscribers at said remotesite; (d) at least one remote site concentrator and associated controlunit located at said remote site and responsive to said plurality ofincoming telephone lines; (e) a central site concentrator located atsaid central site; (f) a plurality of trunk lines connecting saidcentral site concentrator to said remote site concentrator; (g) aplurality of operator positions at said central site, each includingtelephone receiving and transmitting means for answering calls; (h)visual data display means at each of said operator positions fordisplaying alphanumeric data pertaining to an individual subscriber; (i)digital computer means at said central site coupled to the visualdisplay means of each of said operator positions; (j) digital datatransmission means connecting said digital computer means to said remotesite control unit; (k) line scanning means included in said remote sitecontrol unit for scanning each of said incoming telephone lines todetermine whether the line should be answered; (l) coupling controlmeans included in said digital computer means for coupling the signal ofa line to be answered via said remote site concentrator and said centralsite concentrator to an operator position; and (m) data storage meansincluded in said digital computer means for storing and recallingalphanumeric digital data relative to subscriber telephone lines, (n)whereby said digital computer means selects and transmits to the visualdisplay means of said operator position alphanumeric digital data fromsaid data storage means which is relative to a called subscriber line topermit the operator to answer the called line. .Iaddend..Iadd.
 12. Thecomputer controlled telephone answering system of claim 11 wherein saiddigital computer means controls the establishment of a subscriber linepath through both said remote site concentrator and said central siteconcentrator to a telephone operator position. .Iaddend..Iadd.
 13. Acomputer controlled telephone answering system serving the subscribersof a telephone company central office comprising:(a) a central site foranswering the telephones of subscribers of a telephone company centraloffice; (b) a plurality of subscriber telephone lines; (c) aconcentrator located at said central site and responsive to saidsubscriber telephone lines; (d) a plurality of operator positions atsaid central site each including telephone receiving and transmittingmeans for answering calls; (e) visual display means at each of saidoperator positions for displaying alphanumeric data pertaining to anindividual subscriber; (f) digital computer means at said central sitecoupled to the visual display means of each of said operator positions;(g) line scanning means for scanning each of said subscriber telephonelines to determine whether a line should be answered; (h) couplingcontrol means for controlling the coupling of a a signal of a line to beanswered via said central site concentrator to an operator position,said coupling control means being included in said digital computermeans; and (i) data storage means included in said digital computermeans for storing and recalling data relative to subscriber telephonelines; (j) whereby said digital computer means selects and transmits tothe visual display means of said operator position alphanumeric digitaldata from said data storage means which is relative to a calledsubscriber line to permit the operator to answer the called line..Iaddend..Iadd.
 14. The computer controlled telephone answering systemof claim 11 or claim 12 or claim 13 further comprising data entrykeyboard means also at each of said operator positions for recording insaid data storage means alphanumeric messages for later display on theassociated visual display means. .Iaddend..Iadd.
 15. The computercontrolled telephone answering system of claim 11 or claim 12 or claim13 wherein said digital computer means includes operator selecting meansfor selecting an operator position to answer a call. .Iaddend.